A communication system informs terminals of allocated radio resources by using a map transmitted in a downlink for every frame. The map is specified, for example, in an IEEE 802.16 standard.
When bursts are allocated in the downlink and the uplink, the communication system includes a terminal identifier, a transmission method, and a resource used, which correspond to each of the bursts, so as to notify the terminals of the downlink or uplink radio resources.
Further, a plurality of packets that are transmitted from a base station to a plurality of terminals may be allocated as one burst. In this case, a plurality of terminal identifiers corresponding to the packets are omitted. Each of the terminals demodulates the corresponding burst, checks the identifier included in each of the packets, and selectively receives only the packet corresponding to the terminal.
According to the above-described burst allocation, since all of the terminals need to receive the burst, each of the terminals needs to perform a process of receiving the burst even if there is no packet corresponding to the terminal.
Further, in a case of the uplink, it is necessary to provide exact positions of the radio resources to be transmitted by the terminals such that the bursts can be transmitted by the terminals without collision therebetween. Therefore, the burst allocation cannot be applied to the uplink.
Furthermore, when a hybrid automatic repeat request (referred to as an “HARQ” is applied, each terminal may successfully receive a group burst or fail to receive the group burst. Therefore, the burst needs to be retransmitted a maximum number of times or until all of the terminals succeed in receiving the burst.
Further, when multi-input multi-output (hereinafter, referred to as “MIMO” is applied, all of the terminals have different channel states, which makes it difficult to efficiently apply a closed-loop MIMO method.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the related art that is already known in this country to a person of ordinary skill in the art.